The vertical take-off interceptor would reach 8 km altitude in 53 seconds and then manoeuvre toward the aircraft to be intercepted. The design was developed further by Fieseler as the Fi-166, which retained the rocket takeoff but used a turbojet for a longer cruising flight. The Ministry finally rejected the vertical-takeoff rocket interceptor concept at the end of 1941. The concept was revived at the end of the war as the Bachem Natter.